Telephone system



Patented Sept. 6, 1938 v UNITED STATES PATENT OFFICE TELEPHONE SYSTEMDomenico Mastini, Rome, Italy Application April 8 1935, Serial No.15,342 i In Italy March 20, 1935 11 Claims. (Cl. 250-6) My inventionrelates to telephonic or teleremote radio station I and any subscriber 3of graphic connection between two points in which a telephone network,whether of dial or other use is made, for a portion of the distancebetype. tween said points, of any kind of conventional The diagram ofFig. 2 serves to explain the type of telephone network, for example,networks construction shown in Fig. 1. In Fig. 2 there 5 having local orcentral battery, or an automatic is the remote, the stationary ormovable radio system, wireless transmitting means such as elecstation I,the interposed complex I, the teletromagnetic or light waves being usedfor the phone apparatus 9 connected with the local staremainder of.thedistance between two points. tion, and the telephone central 5. Thestation 10 My arrangement requires no change at the cen- I consists of atransmitter I1 and a receiver I9, 10

tral telephone plant, the only change which is with the correspondingaerials. The complex I required being at the individual subscriber'sstaconsists similarly of a stationary wireless transtions where there isadded what I call a committer 2I and a receiver 23, with thecorrespondplex, which is used instead of the ordinary in- .ing aerials.

dividual telephone instrument, there being a con- Two cases are nowpossible: 15 versation connection combined with said com- (1) The radiostation I calls any subscribers plex. station 3.

In the accompanying drawing, by means of (2) Any subscribers station 3calls the radio whichIillustrate my invention, station I.

Fig. 1 is a schematic view exemplifying the In case 1 the conversationcircuit is established 20 general principles of my invention, and in thefollowing manner: As long as a micro- Fig. 2 is a diagram of thecircuits which I phone at the radio station I is hung up, the mayemploy. transmitter ll of station I is inoperative, and

The principle of my invention is first explained both microphone and thetransmitter circuits 25 with reference to Fig. 1, wherein a remote radioare open. Upon the lifting off of the micro- 25 station I, eitherportable or stationary, is to be phone, however, both circuits areclosed by the connected with a particular subscriber station hook 21 andthe transmitter begins to send a 3 through a central station 5. Theradio station carrier wave and, so long as there is no modu- I, throughradiated energy, efiects the remote lation, continues sending thiscarrier wave which control of a complex 'I, which is associated with isreceived by the stationary receiver 23, is am- 30 a telephonesub-station. Under the actuation of plified in high frequency amplifier29, and is this remote control, the complex I is connected passed on toa detector tube 3|. In this case with the central station 5,while theordinary telethe detected high frequency oscillations prophone apparatus9 at the sub-station is disconduce a direct current and this will giverise to nected from the network, and gives rise to a potential at theends of a variable poten- 35 operations in the network circuit of thecentiometer 33 in the cathode circuit of the detral station similar tothose which would have tector. A portion of this potential is passed tobeen produced had the apparatus 9 called the a low frequency amplifier35, while the total apparatus 3 directly. The radiant energy,modpotential drop acts on the grid circuit of a sub- 40 ulated at theremote radio station I, passes to sequent tube 31. This tube. 31 isdirectly cou- 40 the complex I, and the voice-modulated current pledwith an amplifying stage (tube 39), the passes over the previouslyestablished wire confunction of which is to amplify both themoduversation circuit of the telephone network to lated current and thedirect current. the subscriber station 3. A bridge system is provided inthe plate cir- Conversely, an incoming call made from any cuit of thetube .39 across the points (apices) 4,5 subscribers station Will actuatea transmitter in of which there is connected an impulse relay 4| thecomplex 1 tuned to the receiver circuit of which is connected in serieswith a milliamthe remote radio station I, which transmitter, meter 43.By suitably adjusting a regulating rethrough the radiated energy,actuates a receiver sistance 45 in the bridge, the latter, in the abinthe remote station I and upon response of the sence of a carrier wave.can be set to zero, or 50 latter, completes the conversation circuit I3.balanced.

My inventive concept is explained in greater On the other hand, ifacarrier wave is transdetail with reference to Fig. 2 of the drawing.mitted, a potential variation will take place, the This figurediagrammatically shows a combined bridge is no longer in balance, themilliammeter radio-telephone network connection between a indicates thepassage of current, the relay II is 55 excited and closes the feedcircuit of a relay 41. The relay 41, with the switches 49 and 5|, shiftsthe telephone line, consisting of the wires 53 and 55, to the non-localcircuit, these wires 53 and 55 being then connected through twotransformers 51 and 59 with the output circuit of the stationaryreceiver 23 and with the input circuit of the stationary transmitter 2|.The same relay 41, through a contact 6|, also actuates the stationtransmitter 2|. An armature 63 also closes the circuit to the centralstation 5 and opens a shunt circuit normally across the transformer 59.

Calling impulses coming in from station I may then be sent over the lineto the central station.

The oscillator grid circuit of the transmitter I1 is connected to themovable element 65 and to the upper contact 61 of a dialing device 69;A:

lower contact 1| is also associated with the element 65 and theterminals of a grid biasing bat-. tery 13 are connected, respectively,to the contacts.

The grid biasing battery, therefore,,is intere mittently interposed inthe grid circuit of the oscillator by actuation of the dialing device,the polarity of the battery and its potential being such that the gridreceives a blocking negative voltage when the said battery is incircuit. When the element 65 is in the position of rest, as shown in thedrawing, the oscillator may function normally.

The interruptions of the oscillating current, or of the carrier wave,corresponding to the desired subscribers number, operate, at thereceiver 23, to cause the relay 4| to vibrate and thus impose upon thetelephone lines 53-55 the number of pulses required for the calling ofthe desired subscriber 3.

When this is done and the subscribers station 3 is not busy,conversation can be begun, as the modulations coming from themovabletransmitter are sent into the wire circuit by the stationary receiver 23and the coupling transformer 51, while the modulations emitted by thewire circuit pass through the coupling transformer 59 to the stationarytransmitter 2| and from there, by wireless, to the movable receiver I9.

In the second case (2), when the call goes out from any subscriber 3 ofthe telephone network a slow release relay 15is actuated thereby. Thisrelay is of the thermic type and, after being energized, holds thearmature attracted for thirty seconds or for any other suitable periodof time. A contact 11 of this relay actuates the transmitter T and acontact!!! actuates a buzzer 8|, in the grid circuit of transmitter 2|.The transmitter 2|, therefore, will send oscillations, which aremodulated by the inherent frequency of the buzzer and which are receivedby the movable receiver I9 and passed to the associated telephoneapparatus 83. There they produce a call and, if it corresponds to thenumber of the sta-.

tion I and is answered, microphone 25 will be taken off. As a result,the movable transmitter |1 now sends a carrier wave which, afteramplification and reception through the stationary receiver 23, actuatesthe relay 4| therein, which establishes the conversation circuit. Relay4| actuates relay 41 which switches in the telephone line and at thesame time closes the feed circuit of the stationary transmitter 2|,which was previously closed for a short time throughthe relay 15. Afterthese operations the wireless conversation circuit is 'estabilshed.

When the telephone network is manual rather than of the dial type,the-plant issimplifiedflit' being suflicient to establish connectionwith the central exchange in the manner described previously, and, in acentral having local batteries, to send out another calling current.

The circuit described herein only by way of example may be modified indifferent ways. For example, other rays, for example, light rays, may beemployed instead of radio connections.

I claim as my invention:

1. In combination, a remote radio transmitter, a local telephonesub-station, a central station, wire lines normally interposed betweensaid local sub-station and said central station, local radio receivingapparatus and means whereby radio signals received by said localreceiving apparatus from said remote radio transmitter cause thedisconnection of the local sub-station from the wire lines and theconnection of the radio receiving apparatus thereto instead.

2. In combination, a remote radio transmitter, a local radiotransmitter, a local radio receiver, a local telephone sub-station,acentral telephone station, Wire lines normally connecting saidsubstation to said central station, and means responsive to an incomingradio signal, from said remote station, for causing the sub-station tobe disconnected from said wire lines and for causing the connection tosaid lines of said local radio transmitter and said local radioreceiver.

3. In combination, a remote radio transmitter, a local radiotransmitter, a local radio receiver, a local telephone sub-station, acentral telephone station, wire lines normally connecting saidsubstation to said central station, and means whereby a signal from saidremote transmitter, after demodulation by said local receiver, causesthe disconnection of said wire lines from said substation, theconnection of said local radio receiver and said local radio transmitterto said wire lines and the energization of said local transmitter.

4.. Incombination, a remote :radio transmitting and receiving station, alocal radio transmitting and receiving station situated near a localtelephone sub-station, a central station, wire lines normally interposedbetween said local substation and said central station, and means bywhich the local radio transmitting and receiving station, by the actionof the energy transmitted from the remote radio transmitting andreceiving station, is connected to the central station and the localtelephone sub-station is disconnected.

I 5. In combination, a central telephone station,

a telephone sub-station, two wire lines normally connecting thesub-station and the central station, a local radio transmitter andreceiver associated with the sub-station, a remote radio transmitter andmeans for disconnecting said sub-station from said wire lines andconnecting said local transmitter and receiver thereto in lieu thereof,said means being responsive to radiant energy received from said distantradio transmitter.

6. In combination, a central telephone station, a sub-station, two wirelines extending from the central station to the sub-station, a localradio transmitter and receiver disposed in proximity to the sub-station,a remote radio transmitter and receiver, means whereby a carrier wavereceived by the local radio receiver causes disconnection of thesub-station from the lines and connection to said lines of the'localradio transmitter and receiver as well as energization of the localtransmitter and means at the remote transmitter for producing callingimpulseswhereby said remote radio transmitter and receiver may be placedin communication with a predetermined sub-station associated with saidcentral station.

'7. In combination, a central telephone station a sub-station, acommunication channel, constituted by at least two wires, extending fromthe central station to the sub-station, a local radio transmitter andreceiver disposed in proximity to the sub-station, a remotely disposedradio transmitter and means associated with said local radio transmitterand receiver for operatively connecting both of them to saidcommunication channel and for disconnecting the sub-station therefrom inresponse to the reception by said local receiver of a carrier wave fromsaid remote transmitter, said means, upon cessation of said carrierwave, also functioning to disconnect said local transmitter and receiverfrom said communication channel and to reconnect the substation thereto.

8. In combination, a remote radio transmitting and receiving station, alocal radio transmitting and receiving station situated near a localtelephone sub-station, a central station, wire lines normally interposedbetween said local substation and the central station, means by whichthe local radio transmitting and receiving station, by the action of theenergy transmitted from the remote radio transmitting and receivingstation, is connected to the central station and the local telephonestation disconnected, means for transmitting a calling signal, meansresponsive to said calling signal for producing momentary energizationof the local transmitter, and a signal device at said local sub-stationenergized by said signal, said last-named means and said device beingoperative contemporaneously.

9. In combination, a remote radio transmitting and receiving station, alocal radio transmitting and receiving station situated near a localtelephone sub-station, a central station, wire lines normally interposedbetween said local substation and the central station, means by whichthe local radio transmitting and receiving station, by the action of theenergy transmitted from the remote radio transmitting and receivingstation is connected to the central station and the local telephonestation disconnected, means for producing momentary energization of thelocal transmitter and for modulating the carrier wave of the local radiotransmitter for sending to the remote radio receiver a calling signal,and a signal device at the local sub-station, both said device and saidlastnamed means being activated by a calling signal coming from thecentral station.

10. In combination, a remote radio transmitting and receiving station, alocal radio transmitting and receiving station situated near a localtelephone sub-station, a central station, wire lines normally interposedbetween said local station and the central station, means by which thelocal radio transmitting and receiving station, by

the action of the energy transmitted from the remote radio transmittingand receiving station is connected to the central station and the localtelephone station disconnected, means for producing momentaryenergization of the local transmitter and for modulating the carrierwave of the local radio transmitter for sending to the remote radioreceiver a calling signal, a signal device at the local sub-station,both said device and said last-named means being activated by a callingsignal coming from the central station, and means for disabling saidmeans for producing momentary energization in response to said energyreceived from the remote radio station.

11. In combination, a remote radio transmitting and receiving station, alocal radio transmitting and receiving station situated near a localtelephone sub-station, a central station, wire lines normally interposedbetween said local station,

and the central station, means by which the local radio transmitting andreceiving station, by the action of the energy transmitted from theremote radio transmitting and receiving station is connected to thecentral station and the local telephone station disconnected, means forproducing momentary energization of the local transmitter and formodulating the carrier wave of the local radio transmitter for sendingto the remote radio receiver a calling signal, a signal device at thelocal sub-station, both said device and said lastnamed means beingactivated by a calling signal coming from the central station, and meansfor disabling said means for producing momentary energization inresponse to said energy received from the remote radio station and meansat the remote radio transmitter for producing carrier wave impulseswhich after demodulation by the local radio receiver are sent to thecentral station for selecting and calling the desired subscriberstation.

DOMENICO MASTINI.

